diff options
Diffstat (limited to 'library/std/src/sys/unix')
| -rw-r--r-- | library/std/src/sys/unix/kernel_copy.rs | 18 | ||||
| -rw-r--r-- | library/std/src/sys/unix/mod.rs | 52 | ||||
| -rw-r--r-- | library/std/src/sys/unix/rand.rs | 15 | ||||
| -rw-r--r-- | library/std/src/sys/unix/weak.rs | 66 |
4 files changed, 127 insertions, 24 deletions
diff --git a/library/std/src/sys/unix/kernel_copy.rs b/library/std/src/sys/unix/kernel_copy.rs index ac2fcfcb53f..1dc16ef0993 100644 --- a/library/std/src/sys/unix/kernel_copy.rs +++ b/library/std/src/sys/unix/kernel_copy.rs @@ -445,15 +445,15 @@ pub(super) fn copy_regular_files(reader: RawFd, writer: RawFd, max_len: u64) -> // We store the availability in a global to avoid unnecessary syscalls static HAS_COPY_FILE_RANGE: AtomicBool = AtomicBool::new(true); - unsafe fn copy_file_range( - fd_in: libc::c_int, - off_in: *mut libc::loff_t, - fd_out: libc::c_int, - off_out: *mut libc::loff_t, - len: libc::size_t, - flags: libc::c_uint, - ) -> libc::c_long { - libc::syscall(libc::SYS_copy_file_range, fd_in, off_in, fd_out, off_out, len, flags) + syscall! { + fn copy_file_range( + fd_in: libc::c_int, + off_in: *mut libc::loff_t, + fd_out: libc::c_int, + off_out: *mut libc::loff_t, + len: libc::size_t, + flags: libc::c_uint + ) -> libc::ssize_t } let has_copy_file_range = HAS_COPY_FILE_RANGE.load(Ordering::Relaxed); diff --git a/library/std/src/sys/unix/mod.rs b/library/std/src/sys/unix/mod.rs index 7609afbdd76..f8a5ee89969 100644 --- a/library/std/src/sys/unix/mod.rs +++ b/library/std/src/sys/unix/mod.rs @@ -236,3 +236,55 @@ pub fn cvt_nz(error: libc::c_int) -> crate::io::Result<()> { pub fn abort_internal() -> ! { unsafe { libc::abort() } } + +cfg_if::cfg_if! { + if #[cfg(target_os = "android")] { + #[link(name = "dl")] + #[link(name = "log")] + #[link(name = "gcc")] + extern "C" {} + } else if #[cfg(target_os = "freebsd")] { + #[link(name = "execinfo")] + #[link(name = "pthread")] + extern "C" {} + } else if #[cfg(target_os = "netbsd")] { + #[link(name = "pthread")] + #[link(name = "rt")] + extern "C" {} + } else if #[cfg(any(target_os = "dragonfly", target_os = "openbsd"))] { + #[link(name = "pthread")] + extern "C" {} + } else if #[cfg(target_os = "solaris")] { + #[link(name = "socket")] + #[link(name = "posix4")] + #[link(name = "pthread")] + #[link(name = "resolv")] + extern "C" {} + } else if #[cfg(target_os = "illumos")] { + #[link(name = "socket")] + #[link(name = "posix4")] + #[link(name = "pthread")] + #[link(name = "resolv")] + #[link(name = "nsl")] + // Use libumem for the (malloc-compatible) allocator + #[link(name = "umem")] + extern "C" {} + } else if #[cfg(target_os = "macos")] { + #[link(name = "System")] + // res_init and friends require -lresolv on macOS/iOS. + // See #41582 and http://blog.achernya.com/2013/03/os-x-has-silly-libsystem.html + #[link(name = "resolv")] + extern "C" {} + } else if #[cfg(target_os = "ios")] { + #[link(name = "System")] + #[link(name = "objc")] + #[link(name = "Security", kind = "framework")] + #[link(name = "Foundation", kind = "framework")] + #[link(name = "resolv")] + extern "C" {} + } else if #[cfg(target_os = "fuchsia")] { + #[link(name = "zircon")] + #[link(name = "fdio")] + extern "C" {} + } +} diff --git a/library/std/src/sys/unix/rand.rs b/library/std/src/sys/unix/rand.rs index eed6fbf13b7..38ddb41700c 100644 --- a/library/std/src/sys/unix/rand.rs +++ b/library/std/src/sys/unix/rand.rs @@ -25,10 +25,19 @@ mod imp { use crate::io::Read; #[cfg(any(target_os = "linux", target_os = "android"))] - fn getrandom(buf: &mut [u8]) -> libc::c_long { - unsafe { - libc::syscall(libc::SYS_getrandom, buf.as_mut_ptr(), buf.len(), libc::GRND_NONBLOCK) + fn getrandom(buf: &mut [u8]) -> libc::ssize_t { + // A weak symbol allows interposition, e.g. for perf measurements that want to + // disable randomness for consistency. Otherwise, we'll try a raw syscall. + // (`getrandom` was added in glibc 2.25, musl 1.1.20, android API level 28) + syscall! { + fn getrandom( + buffer: *mut libc::c_void, + length: libc::size_t, + flags: libc::c_uint + ) -> libc::ssize_t } + + unsafe { getrandom(buf.as_mut_ptr().cast(), buf.len(), libc::GRND_NONBLOCK) } } #[cfg(not(any(target_os = "linux", target_os = "android")))] diff --git a/library/std/src/sys/unix/weak.rs b/library/std/src/sys/unix/weak.rs index f4b33a00f7c..53d95dca4cd 100644 --- a/library/std/src/sys/unix/weak.rs +++ b/library/std/src/sys/unix/weak.rs @@ -24,7 +24,7 @@ use crate::ffi::CStr; use crate::marker; use crate::mem; -use crate::sync::atomic::{AtomicUsize, Ordering}; +use crate::sync::atomic::{self, AtomicUsize, Ordering}; macro_rules! weak { (fn $name:ident($($t:ty),*) -> $ret:ty) => ( @@ -47,15 +47,49 @@ impl<F> Weak<F> { pub fn get(&self) -> Option<F> { assert_eq!(mem::size_of::<F>(), mem::size_of::<usize>()); unsafe { - if self.addr.load(Ordering::SeqCst) == 1 { - self.addr.store(fetch(self.name), Ordering::SeqCst); - } - match self.addr.load(Ordering::SeqCst) { + // Relaxed is fine here because we fence before reading through the + // pointer (see the comment below). + match self.addr.load(Ordering::Relaxed) { + 1 => self.initialize(), 0 => None, - addr => Some(mem::transmute_copy::<usize, F>(&addr)), + addr => { + let func = mem::transmute_copy::<usize, F>(&addr); + // The caller is presumably going to read through this value + // (by calling the function we've dlsymed). This means we'd + // need to have loaded it with at least C11's consume + // ordering in order to be guaranteed that the data we read + // from the pointer isn't from before the pointer was + // stored. Rust has no equivalent to memory_order_consume, + // so we use an acquire fence (sorry, ARM). + // + // Now, in practice this likely isn't needed even on CPUs + // where relaxed and consume mean different things. The + // symbols we're loading are probably present (or not) at + // init, and even if they aren't the runtime dynamic loader + // is extremely likely have sufficient barriers internally + // (possibly implicitly, for example the ones provided by + // invoking `mprotect`). + // + // That said, none of that's *guaranteed*, and so we fence. + atomic::fence(Ordering::Acquire); + Some(func) + } } } } + + // Cold because it should only happen during first-time initalization. + #[cold] + unsafe fn initialize(&self) -> Option<F> { + let val = fetch(self.name); + // This synchronizes with the acquire fence in `get`. + self.addr.store(val, Ordering::Release); + + match val { + 0 => None, + addr => Some(mem::transmute_copy::<usize, F>(&addr)), + } + } } unsafe fn fetch(name: &str) -> usize { @@ -66,7 +100,7 @@ unsafe fn fetch(name: &str) -> usize { libc::dlsym(libc::RTLD_DEFAULT, name.as_ptr()) as usize } -#[cfg(not(target_os = "linux"))] +#[cfg(not(any(target_os = "linux", target_os = "android")))] macro_rules! syscall { (fn $name:ident($($arg_name:ident: $t:ty),*) -> $ret:ty) => ( unsafe fn $name($($arg_name: $t),*) -> $ret { @@ -84,7 +118,7 @@ macro_rules! syscall { ) } -#[cfg(target_os = "linux")] +#[cfg(any(target_os = "linux", target_os = "android"))] macro_rules! syscall { (fn $name:ident($($arg_name:ident: $t:ty),*) -> $ret:ty) => ( unsafe fn $name($($arg_name:$t),*) -> $ret { @@ -92,10 +126,18 @@ macro_rules! syscall { // (not paths). use libc::*; - syscall( - concat_idents!(SYS_, $name), - $($arg_name as c_long),* - ) as $ret + weak! { fn $name($($t),*) -> $ret } + + // Use a weak symbol from libc when possible, allowing `LD_PRELOAD` + // interposition, but if it's not found just use a raw syscall. + if let Some(fun) = $name.get() { + fun($($arg_name),*) + } else { + syscall( + concat_idents!(SYS_, $name), + $($arg_name as c_long),* + ) as $ret + } } ) } |